Many researches are being conducted to provide various types of multimedia services including voice services and to support high-speed data transmission in a wireless communication environment. As part of the effort, technology associated with a Multiple-Input Multiple-Output (MIMO) system using multiple channels in a spatial area is in rapid development.
MIMO technology may increase the number of channel bits in limited frequency resources and thereby provide a high data rate using multiple antennas. Also, since MIMO technology uses a plurality of transmitting/receiving antennas in a channel environment with sufficient scattering bodies, MIMO technology may theoretically provide channel capacity in proportion to a fewer number of antennas between a number of transmitting antennas and a number of receiving antennas.
In a MIMO communication system, a plurality of paths exists between a transmitter and a receiver. Transmission symbols of the transmitter may be transmitted to the receiver via the plurality of paths. For examples, where a number of antennas of the transmitter and a number of antennas of the receiver are “4”, vector Y consisting of received symbols may be represented as,
                                                        Y              =                              [                                                                                                    y                        1                                                                                                                                                y                        2                                                                                                                                                y                        3                                                                                                                                                y                        4                                                                                            ]                                                                                        =                                                                    [                                                                                                                        h                            11                                                                                                                                h                            12                                                                                                                                h                            13                                                                                                                                h                            14                                                                                                                                                                            h                            21                                                                                                                                h                            22                                                                                                                                h                            23                                                                                                                                h                            24                                                                                                                                                                            h                            31                                                                                                                                h                            32                                                                                                                                h                            33                                                                                                                                h                            34                                                                                                                                                                            h                            41                                                                                                                                h                            42                                                                                                                                h                            43                                                                                                                                h                            44                                                                                                                ]                                    ⁡                                      [                                                                                                                        x                            1                                                                                                                                                                            x                            2                                                                                                                                                                            x                            3                                                                                                                                                                            x                            4                                                                                                                ]                                                  +                                  [                                                                                                              n                          1                                                                                                                                                              n                          2                                                                                                                                                              n                          3                                                                                                                                                              n                          4                                                                                                      ]                                                                                                        =                              HX                +                N                                                                        [                  Equation          ⁢                                          ⁢          1                ]            
where x1, x2, x3,and x4 are transmission symbols, hab is a channel coefficient corresponding to a path until a bth transmission symbol reaches an ath receiving antenna, and n1, n2, n3, and n4 are noise.
The receiver may separate received symbols for each substream and detect transmission symbols based on the separated received symbols. However, since multi-path interference occurs between a plurality of paths and multi-path interference corresponding to each of the plurality of paths is independent, it is difficult to accurately detect the received symbols. In addition, distortion by the multi-path interference makes it difficult to accurately detect the received symbols.